The present disclosure relates to a protection apparatus and a method of verifying an operation thereof, and more particularly, to a method of verifying an operation of a protection apparatus for an AC filter or converter transformer used in a high voltage direct current (HVDC) system.
A high voltage direct current (HVDC) system is used for long-distance transmission and transmission of electric power using underwater power cables. Since the HVDC system generates reactive power and harmonic waves while converting electric power using a converter, it needs an AC filter.
To optimize operations of the AC filter that may be damaged by various factors and protect the AC filter, a protection apparatus including a specific relay and a protection panel is implemented.
Particularly, the relay is a device to open or close an electric circuit depending on various input signals, such as temperature, light, and the like as well as electric signals, such as voltage, current, power, frequency, and the like, and has various purposes as well as a general control purpose. Such a relay is required to satisfy conditions, such as high reliability, long lifespan, high sensitivity, and the like, and for satisfying such conditions, tests for verifying operation characteristics according to subjects of application are required.
The protection apparatus may realize high reliability of the HVDC system by protecting the AC filter or an inner circuit of a converter transformer bank through verification of relay elements, such as percentage differential, unbalanced current, harmonic overload, overcurrent, ground overcurrent relay elements. Therefore, a test for verifying performances of the AC filter or a protection relay and a protection panel of the converter transformer is essential and an important issue.